I'm not sure that i have understood correctly what the links say.
Let's make an example.
- I have an electrum wallet with 1 btc and its own seed and Passphrase , and an other electrum wallet whit 2 btc with its own seed and Passphrase .
- I buy a trezor. I create a new btc seed for my trezor.
So far... so good.
- I send my 3 btc to trezor, so, all of these btc have now only a seed and no Passphrase.
No... I do not recommend that you do this...
- Then i enable Passphrase encryption on my trezor.
- Then i can create two different Passphrase and send 1 btc to my first Passphrase wallet and 2 btc to my second Passphrase wallet.
- So, after that, i have to wallet with two different amount on them.
You should just do this... create the passphrases FIRST... then transfer 1 btc from "ElectrumWallet1" to "TrezorPassphraseWallet1"... and 2 btc from "ElectrumWallet2" to "TrezorPassphraseWallet2"... or, as I stated earlier, you can simply create multiple accounts in Trezor. Refer:
https://blog.trezor.io/wallet-accounts-and-addresses-bdfa6b66b037 - The section on "Accounts". You can have up to 10 BTC "accounts" in your wallet... it's a bit like having a checking account and a savings account. The accounts are "separate"... ie. you cannot create a transaction that includes coins from Account#0 with coins from Account#1 in the same transaction... but all the accounts are generated from the same seed/passphrase.
If i want to import my trezor's seed on a new electrum wallet, what happen? I will see a wallet with 3 btc, or what else? I don't understand this part
To import the seed into a new Electrum wallet, you would enter the seed, click "options", select "BIP39 seed" and "Extend this seed with custom words"... you'd put your seed in, then on the next screen, you're prompted for the "extra words"... this is your "passphrase".
So you would need to create 2 new Electrum wallets... one for each "passphrase"...
If you use the "account" method, you'd still need to create 2 new Electrum wallets when restoring to Electrum, but instead of having passphrases, you'd simply change the Derivation Path (m/44'/0'/1'... m/44'/0'/2' etc).
An other question: is it more safe use a Passphrase on trezor?
I'm not sure what you mean here? Using a passphrase means you can effectively "hide" your actual wallet... someone could have your 24 word seed, but without your passphrase they will never find your actual wallet... bruteforcing a "strong" password (10+ alphanumerics+symbols) is impractical for current computers (length of time required measured in years etc)... so if your piece of paper with your seed words gets stolen, and you've used a passphrase, you have plenty of time to move your coins before the thief can access them. Without a passphrase, as soon as they have your seed, they effectively own your coins